Indicator for the titration of $HCl$ and $Na_2CO_3$ would be

Starch can be used as an indicator for the detection of traces of

Phenolphthalein is not suitable for the titration of

For an acid-base indicator,the dissociation constant $K_a = 1.0 \times 10^{-5}$. The indicator is red in acidic form and blue in basic form. What is the $pH$ range required for the color change from $80\%$ red to $80\%$ blue?

Phenolphthalein is a.......

Which indicator is most suitable for the titration of $0.1 \, N \, Na_2CO_3$ solution with $0.1 \, N \, HCl$?